Steerable medical device

ABSTRACT

An elongate steerable implement is disclosed, which may be either a steerable guidewire or catheter for coronary angioplasty applications. A floppy steerable tip on a steering region at the distal end of the implement and a control device at the proximal end are connected by means of a plurality of axially movable deflection wires extending throughout the implement. Manipulation of the control permits deflection of the steering region throughout a full 360° range of motion about the axis of the implement, without axial rotation or &#34;torquing&#34; thereof. In another embodiment, a steering ribbon is disclosed which permits steering by lateral deflection of the tip into a deflected or bent position and then permits straightening the tip back to its original position.

BACKGROUND OF THE INVENTION

This is a continuation-in-part of U.S. patent application Ser. No.461,049, filed Jan. 4, 1990, now issued as U.S. Pat. No. 4,998,916inventors Julius G. Hammerslag and Gary R. Hammerslag, entitled"Steerable Medical Device;" which is a continuation-in-part of parentU.S. patent application Ser. No. 295,124, filed Jan. 9, 1989; now U.S.Pat. No. 4,921,482 inventors Julius G. Hammerslag and Gary R.Hammerslag, entitled "Steerable Angioplasty Device."

The present invention relates to steering devices such as may be usedwith catheters, cannulae, guidewires and the like. More particularly,the present invention relates to catheters and guidewires that aresteerable through body lumen or cavities and positionable within oraimable at obstructions, organs or tissue within the body from aposition external to the body.

Medical catheters generally comprise elongate tube-like members whichmay be inserted into the body, either percutaneously or via a bodyorifice, for any of a wide variety of diagnostic and therapeuticpurposes. Such medical applications frequently require use of a catheterhaving the ability to negotiate twists and turns, particularly withregard to certain cardiovascular applications.

One such application, "Percutaneous Transluminal Coronary Angioplasty"(balloon angioplasty), requires manipulation of a catheter from aposition outside the patient's body through extended portions of thepatient's arterial system to the stenotic site for the purpose ofalleviating the obstruction by inflating a balloon. This particularprocedure has been performed with increasing frequency over the pastyears in preference to open heart bypass surgery, when possible.

In a typical angioplasty procedure, a guidewire is transluminallyinserted into the brachial or the femoral artery, to be positionedwithin the stenotic region and followed by a balloon catheter. Thecardiologist usually pre-bends the distal tip of the guidewire beforeinsertion and then rotates (or torques) the wire once it has reached abranch artery to enable the guidewire to enter the branch. If the angleof the bend has to be adjusted, the guidewire must be removed, re-bentand reinserted, sometimes several times. Particular difficulty isencountered with prebending where an artery branches at one angle, andthen sub-branches at a different angle. This procedure is attended bythe risk of significant trauma to the arterial lining, and, in manycases, the obstruction cannot be reached at all with the guidewire andcatheter.

Coronary arteries are tortuous, have many sub-branches and often theobstruction is either located where the diameter of the artery is smallor, by its very presence, the obstruction leaves only a very smallopening through which a guidewire and/or catheter can be passed.Consequently, the cardiologist often finds it very difficult to maneuverthe guidewire or catheter, which are typically several feet long, fromthe proximal end.

Steering the pre-bent guidewire is further complicated by the fact thatbranches project at all different radial angles, thus necessitatingrotation of the guidewire to the appropriate degree to enter the desiredarterial branch. However, rotation of the distal end of the wiretypically lags behind rotation of the proximal, control end, so thatprecise rotational control is not possible. Also, friction in thearteries can cause the distal end to rotate in a jerky fashion which cantraumatize the vascular intima.

In another application, Transluminal Laser Catheter Angioplasty (laserangioplasty), the delivery of laser energy from an external source to anintraluminal site to remove plaque or thrombus obstructions in vesselsis accomplished by providing a waveguide such as a fiber optic bundlewithin a catheter. The nature of laser angioplasty requires an evengreater ability to precisely manipulate the catheter, to control and aimthe laser light at the specific plaques or thrombi to be removed.

A variety of attempts have been made in the past to provide catheterswhich are steerable from the proximal end to enable the catheter to beaimed or advanced through non-linear body cavities. For example, U.S.Pat. No. 4,723,936 to Buchbinder, et al. discloses a balloon catheter,which is said to be steerable from the proximal end. The catheter isprovided with a deflection wire going along the entire length of thecatheter, which may be axially displaced to cause deflection at thedistal end. However, the tip of the catheter can be bent in onedirection only, and the entire catheter must be rotated or torqued to beguided. A further disadvantage of this device is the inability toeffectively straighten the catheter once it has been bent. Any abilityof the Buchbinder catheter depends upon the axial compression of thesteering wire therein. In addition, the design requires a relativelylarge diameter deflection wire, which precludes extremely thin diametercatheters, such as those preferred for use for laser or balloonangioplasty applications.

U.S. Pat. No. 3,470,876 to Barchilon discloses a catheter device havinga central lumen extending therethrough, and four tensioning cordsextending along an inner wall of the catheter. The '876 patentspecifically recites that catheters may be produced in accordance withthe Barchilon design having diameters of 0.125 to 2 inches, and aresuited for applications such as within the duodenal bulb or ascendingcolon. These diameters are unsuited for use as a guidewire in coronaryangioplasty, which typically requires diameters in the area of as smallas from about 0.014 to 0.018 inches.

In the context of coronary angioplasty applications, the prior artgenerally suffers from disadvantages such as limited steerability andexcessive external diameters. Limited catheter tip steerability resultsin greater time spent in the body and significantly elevated risk oftrauma both to the vascular intima and to the patient in general.Multiple insertions of guidewires or catheters may lead to thrombosis,as a result of coagulation commencing along a guidewire surface.Additionally, precise directional control in laser angioplasty is of theutmost importance to assure accurate aiming of the laser beam to ablatethe attendant plaque. However, the only prior art catheters havingmulti-directional steerability are typically greatly in excess ofpractical angioplasty catheter diameters.

In addition to limited steerability, the prior art guidewires, such asthose disclosed by Buchbinder and in U.S. Pat. No. 4,719,924 toCrittenden, rely upon the spring tension of the guidewire coil (and theresilience of the distal end of the deflection wire, in the case ofBuchbinder) to return the guidewire to the straight, unbent position.However, as important as deflecting the wire to enter a branch artery isstraightening the wire after the branch is negotiated. Any ability tostraighten in the prior art devices described above results from thespring tension or other structure in the distal end of the wire, whichstructures also compromise the desired floppiness of the guidewire tip.

Thus, there remains a need for a small diameter steering device, whichmay be readily adapted for use in the construction of either guidewiresor catheters, and which is especially suited for procedures such asballoon or laser angioplasty. Preferably, the steering device isconstructed in a manner which permits a diameter as small as that ofexisting dilatation catheters or guidewires used in angioplastyapplications, yet is capable of complete deflective movement, throughouta full 360° range of motion, without axial rotation.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, there isprovided an improved steerable guidewire or catheter implement of thetype useful for percutaneous transluminal insertion into the coronaryvascular system. The invention permits controlled negotiation ofbranches and turns to guide an angioplasty catheter or guidewire to anarterial stenosis or lesion or other treatment site without the need forprebending or torquing of the instrument. The distal tip on steerableimplements made in accordance with one embodiment of the presentinvention can be controllably radially displaced in any direction, thuspermitting a full 360° range of motion without the need to rotate thebody of the steerable implement.

In one embodiment of the present invention, a guidewire is providedhaving an elongate flexible shaft with a central lumen extendingtherethrough and a floppy resilient tip on the distal end. An axiallyextending steering post is disposed within a steering region on thedistal portion of the flexible shaft. The steering post is pivotablysecured at its proximal end to a radial support axially secured withinthe flexible shaft at the proximal end of the steering region, toprevent axial displacement of the steering post while at the same timepermitting lateral deflection of the steering post out of parallel withthe axis of the flexible shaft.

At least one and preferably two or three or four deflection wires areaxially movably disposed within the lumen of the flexible shaft, andextend proximally from a distal point of attachment on the steering postthroughout the length of the flexible shaft to a control at the proximalend thereof. Each deflection wire passes through a notch or orifice onthe radial support.

In another embodiment, the steering post is provided with a wire anchorregion at its distal end and a wire guide region at its proximal end.Preferably, the cross-sectional area of the post at a point intermediatethe anchor region and guide region is less than the cross-sectional areaof the post at least one of the anchor region and guide region, and,more preferably, is less than the cross-sectional area of the post atboth the guide region and anchor region.

In a further embodiment, a deflection wire anchor is disposed in thesteering region of the flexible shaft, spaced apart in a distaldirection from a deflection wire guide. Preferably, opposing pairs ofdeflection wires are formed by providing a continuous length of wirewhich loops at its midpoint across the distal end of the anchor, bothends extending through the flexible shaft in a proximal direction.

Axial movement of any one of the deflection wires in a proximaldirection displaces the axis of the steering post in a unique lateraldirection, and through combinations of proximal axial displacement ofmore than two deflection wires, the steering post is caused to deflectlaterally and rotate throughout a full 360° range of motion about theaxis of the flexible shaft. In a two wire embodiment, the deflectionwires are preferably disposed in parallel to and on opposite sides ofthe longitudinal axis of the device to permit bending the tip by pullingon one wire and straightening the tip by pulling on the other wire.

The steerable medical device of the present invention can thus negotiatetortuous and branched arterial systems, without the need for withdrawaland multiple insertions to deflect the tip, or axial rotation of thecatheter body. The steerable medical device can be readily manufacturedin accordance with known techniques, and at a low per unit cost.

These and other features and advantages of the present invention willbecome apparent from the detailed description of preferred embodimentswhich follows, when considered together with the attached drawings andclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial sectional perspective view of a steerable guidewireaccording to the present invention, with the outer tubular casingremoved.

FIG. 2 is an elevational sectional view of the guidewire of FIG. 1,illustrated in a first deflected position.

FIG. 3 is an elevational sectional view of the guidewire of FIG. 1,illustrated in a second deflected position.

FIG. 4 is a partial sectional perspective view of a steerable laserangioplasty catheter according to the present invention.

FIG. 5 is a further embodiment of the steerable guidewire of the presentinvention.

FIG. 6 is a schematic view of the guidewire of FIG. 1, illustrated asnegotiating an arterial branch point and approaching an arterialstenosis.

FIG. 7 is an elevational perspective view of a further embodiment of asteering device according to the present invention.

FIG. 8 is an elevational perspective view of still a further embodimentof the present invention.

FIG. 9 is a cross-sectional view along the line 9--9 of the device ofFIG. 8.

FIG. 10 is a simplified front elevational view of the device shown inFIG. 8, following application of an anchor cap.

FIG. 11 is a simplified front elevational view of the device shown inFIG. 7, following application of an anchor cap.

FIG. 12 is a partial sectional perspective view of a simplified steeringdevice according to the present invention, with the outer tubular casingremoved.

FIG. 13 is an elevational perspective view of a another embodiment of asimplified steering device according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, there is disclosed an elongate flexible implement10, having a tubular body 11 with a proximal end 12 and a distal end 14.The distal end 14 comprises a steering region 16, and the proximal end12 is provided with a control 18 for steering the implement 10, whichmay be, for example, a steerable guidewire or catheter. Although thesteering device of the present invention will generally be describedherein as incorporated into an angioplasty guidewire, it is to beunderstood that one skilled in the art will be able to readily adapt thesteering device to other medical and non-medical applications.

The body 11 of steerable implement 10 may be any desired length frominches to many feet depending upon the intended application. In anembodiment useful as an angioplasty guidewire or catheter, the body 11will typically be several feet long, and will preferably be about135-180 cm, as is typical of existing angioplasty catheters andguidewires respectively. However, any suitable length may be used.

The body 11 may be constructed in any of a variety of ways known in theart, such as by tightly winding a coil of metal wire, or extrusion of arelatively flexible biocompatible polymer such as polyethylene. Woundguidewires preferably comprise a high tensile strength wire of aresilient, non-corrosive metal such as stainless steel or platinum, andmay have a circular cross-section with a diameter of from about 0.001 to0.020 in. The wire may alternatively have a rectangular cross-section offrom about 0.001 to 0.020 inches by from about 0.001 to 0.040 inches, orother variations known in the art. Construction materials and techniquesfor manufacturing wire wound guidewires are well known in the art, and atypical 180 cm teflon coated 0.014 inch or 0.016 inch diameternon-steerable guidewire may be obtained from U.S. Catheter, Inc., adivision of C.R. Bard, Inc., located in Billerica, Mass. U.S.A.

The external diameter of wire wound guidewires will of course be afunction of the intended application. The wire wound coronaryangioplasty guidewires incorporating the steering device of the presentinvention are preferably wound to have an external diameter in the rangeof from about 0.014 inches to about 0.018 inches. In steerable catheterapplications, the diameter of the catheter can be varied to optimize thediameter of a central working channel as desired, while stillmaintaining a sufficiently small exterior diameter for the intendedapplication. Steerable balloon angioplasty catheters incorporating thepresent invention will typically have an exterior diameter in the rangeof from about 0.020 inches to about 0.041 inches or larger as permittedby location of the lesion.

Preferably, the exterior surface of the wound coil type guidewire shaft10 is provided with an elastic, biocompatible coating or sheath toprovide a smooth outer surface. Suitable coatings can be formed bydipping, spraying or wrapping and heat curing operations as are known inthe art. Alternatively, heat shrinkable tubing can provide a suitableouter sheath. A coating material should be selected which will permitsufficient flexing of the body 11 without cracking, will minimizesliding friction of the implement 10 during insertion and removal, andis substantially chemically inert in the in vivo vascular environment. Avariety of suitable materials are known, including, for example,polytetrafluoroethylene, urethane or polyethylene.

The body 11 of flexible implement 10 typically terminates at its distalend 14 in a closed tip 20. Numerous guidewire and catheter tipconstructions are known in the art and need not be detailed extensivelyherein. In general, the tip 20 is preferably a rounded closureconstructed of a resilient polymeric material such as silicone orurethane which will minimize trauma to the vascular intima, as will beappreciated by one of skill in the art. As a safety feature, tofacilitate complete removal of fragments of a broken guidewire, a safetywire may be secured at one end to the inside of the tip 20, and at theother end to the post 22 or support 24.

Disposed intermediate the tip 20 and body 11 of a flexible implement 10in accordance with the present invention is a floppy but controllablesteering region 16. Steering region 16 is constructed in a manner thatfacilitates lateral displacement of the tip 20 relative to the axis ofthe body 11, through physical design and/or choice of flexibleconstruction materials.

For example, in a typical angioplasty guidewire or catheter, where theflexible body 11 comprises a metal wire coil, the revolutions of wireper unit of axial distance along the body is reduced in the steeringregion 16 relative to body 11 to provide a looser wound coil havingspace 17 between adjacent wire loops, as illustrated in FIGS. 1-6. Thus,referring to FIG. 2, it can be seen that lateral deflection of steeringregion 16 to the left may involve both an axial compression of adjacentwire loops on the inside surface 36 of the bend, and an axial separationof the adjacent wire loops on the outside surface 38 of the bend.

Alternative designs or materials can be employed, provided that thecatheter exhibits sufficient lateral flexibility. In general, thesteering region 16 may be made from a variety of suitable metal orplastic coils or flexible sleeves. Materials opaque to X-rays, such asplatinum, gold, tungsten, tantalum or the like, may be advantageouslyincorporated therein, to act as a fluoroscopic marker to aid invisualization.

In accordance with the steering mechanism of the present invention, asteering post 22 is provided, extending in a generally axial directionwithin the steering region 16 of flexible body 11. Preferably, thesteering post 22 is disposed coaxially within the central lumen ofsteering region 16 when the steering region 16 and body 11 are linearlyaligned, such as when at rest. See FIG. 1. As will be described, thesteering post 22 is secured in the steering region 16 in a manner thatsubstantially prevents axial displacement thereof yet permits lateraldeflection of the axis of the steering post 22 away from the axis ofbody 11.

Post 22 preferably comprises a resilient shaft which may be molded orextruded from any of a variety of materials, such as nylon, and may havea cross-sectional dimension of from about 0.002 inches up to about 0.012inches for use in a typical steerable angioplasty guidewire embodiment.Alternatively, a variety of resilient or springy metals in the form ofwire can also be used to form post 22, such as phosphor bronze or otherresilient metal. In general, it is desirable to select a material whichwill permit some degree of bending and return to its original shape, andwill resist axial compression under the forces typically applied in theintended use of the steerable implement 10.

The length of steering post 22 will, of course, be dependant upon thelength of the steering region 16. In a typical steerable guidewire forangioplasty applications, the entire steering region 16 will be on theorder of from about 0.040 to about 1.0 inches and preferably from about0.120 to about 0.150 inches long, and the steering post 22 may be fromone-quarter to two-thirds that length. Although steering post 22 mayextend distally all the way to the distal tip 20 of the steerableimplement 10, it is preferred to limit the length to the proximalone-half or one-third of the axial length of steering region 16 tominimize rigidity in the steering region 16 yet permit sufficientsteerability thereof.

For example, in a typical angioplasty guidewire the distal end 27 ofsteering post 22 will be spaced apart from the interior surface of tip20 by a distance of from about one-tenth to one-half an inch or more,thus permitting the steering region 16 of the catheter shaft to be asfloppy as desired. However, in an embodiment where the distal portion ofa fiber optics bundle or flexible tube for defining a working channeladditionally functions as the steering post 22, the post 22 will extendall the way to the distal tip 20 and be exposed to the outside by way ofan opening therethrough. See, for example, FIG. 4.

In a particularly preferred embodiment, steering post 22 is furtherprovided with a bead or enlarged region 26 to optimize transmission oflateral force from the steering post 22 to the wall of steering region16. For this purpose, bead 26 is most effectively located at or near thedistal end of steering post 22. Bead 26 may be formed by dipping orcoating techniques, or may be a preformed member having an openingtherein for sliding over the end of steering post 22. Alternatively,post 22 can be molded or milled to provide a bead 26 integrally formedthereon. Bead 26 is preferably substantially circular in a cross-sectionperpendicular to the axis of post 22, and the external diameter of thebead 26 is only slightly less than the interior diameter of the steeringregion 16 so that maximum lateral motion of the steering post 22 istransmitted to the steering region 16, but bead 26 also remains only inslidable contact with the interior surface thereof.

The proximal end 23 of the steering post 22 is mounted to or inpivotable contact with a radial support 24, in a manner which permitspivoting of the steering post 22 throughout a full 360° range of motionabout the axis of body 11. The post may also be molded or milled as anintegral part of disk 24. The support 24 comprises any means by whichthe deflection wires 28 are displaced radially outwardly from the axisof the tubular body 11, such as by the thickness of the post 22 or otherstructure including the plate embodiment illustrated in FIGS. 1-3.

Referring to FIG. 1, the support 24 of the illustrated embodimentcomprises a circular disk 25 located within the tubular body 11 of thesteerable implement 10, preferably located near the distal end thereof.The disk 25 is axially secured within the tubular body 11 to provide astationary radial support for at least one deflection wire 28, andpivotable mount for steering post 22. Disk 25 may be attached, forexample, by friction fit between adjacent turns of coiled spring wire.Steering post 22 preferably is attached to or in contact with the disk25 in a manner which permits it to swivel from 90 degrees to close to 0degrees, relative to the lateral plane of disk 25.

The disk 25 may be made of stainless steel or any of a variety of othersuitable materials such as other metals or plastic polymers which willprovide a sufficiently axially rigid seat for the proximal end 23 ofsteering post 22. Disk 25 may be formed by stamping from sheet stock anddrilling, injection molding, or other techniques well known in the art.Preferably, a central depression or orifice is provided thereon, forproviding an axial seat for steering post 22. The diameter of disk 25can vary, however, it will typically be no greater than, but mayapproximate the outside diameter of the steerable implement 10.Diameters from about 0.14 to 0.050 inches may preferably be used in theconstruction of cardiac angioplasty catheters.

Lateral deflection of the steering post 22 away from the axis of body 11is accomplished by proximal axial displacement of any of a plurality ofdeflection wires 28 extending proximally throughout the length offlexible body 11. Although only a single deflection wire 28 or twodeflection wires can be used, preferably three or four deflection wires28 are employed to provide a full 360° range of motion of the steeringregion 16 about the axis of the body 11, as will become apparent. Only asingle deflection wire 28 will be described in detail herein.

The distal end of deflection wire 28 is secured such as by adhesives (orbrazing or soldering, etc.) to the steering post 22 at the distal endthereof, or at a variety of other locations along the length of post 22.By "attached" or "secured" to the post and similar language herein, itis to be understood that the deflection wire 28 must be mechanicallylinked to the post 22 but need not necessarily be directly securedthereto. For example, the deflection wire 28 could be secured to anannular flange or ring surrounding the post or other structure which maybe convenient from a manufacturing standpoint to provide a sufficientlysecure linkage to accomplish the intended steering function.Alternatively, an eye on the end of the deflection wire can surround thepost 22 and rest against a stop formed by a milled shoulder or adhesive,or other means of attachment as will be apparent to one of skill in theart.

In one embodiment, the deflection wire 28 preferably extends radiallyoutwardly from the point of attachment to the steering post 22 to thesupport 24. For this purpose, the support 24 is preferably provided witha notch or orifice 40 for each deflection wire 28 to extend through,said orifice 40 spaced radially outwardly from the axis of the tubularbody 11 by a first distance. The distal end of each deflection wire 28is secured to the steering post 22 at a point radially displaced fromthe axis of the steering post 22 by a second distance, and the firstdistance is preferably greater than the second distance to maximize thelateral component of force. The second distance preferably approacheszero; however, it will inherently include the radius of the steeringpost 22 where the deflection wire 28 is secured intermediate the twoends thereof.

In the most preferred embodiment of the present invention, fourdeflection wires 28 are provided, each passing through an orifice 40 insupport 24 spaced at angles of approximately 90° apart from each otheralong the plane of the support 24. In a three deflection wireembodiment, as illustrated in FIG. 1, each orifice 40 is separated fromeach adjacent orifice by an angle of approximately 120°.

The deflection wires may be made of stainless steel, nylon or any othersuitable material which provides sufficient tensile strength andflexibility. The diameter of the lines can range from 0.001 to 0.005inches or more, and suitability of particular sizes or materials can bereadily determined by experimentation.

A control device 18 for steering the catheter is shown schematically inFIGS. 1-3. The control device 18 is preferably provided at its centerwith a pivotable mount 32 to permit it to be tipped throughout a full360° range of motion. In the illustrated embodiment, control 18comprises a circular plate 34 secured to proximal end 12 of flexibleshaft 10 by way of pivotable mount 32. Deflection wires 28 are spacedequally radially outwardly from the pivotable center of the controldevice and at equal angular distances around the plate 34. Deflectingplate 34 from a plane normal to the axis of shaft 10 transmits force viaone or more deflection wires 28, a component of which is resolved into alateral force to deflect the catheter tip toward or away from thelongitudinal axis of catheter. Selective tipping of the deflection plate34 results in rotation of the catheter tip to any desired orientation.

A variety of alternative control devices can be envisioned for use withthe steerable implement of the present invention. For example, a "joystick" type device comprising a single lever which can be displaced toany position throughout a nearly hemispherical range of motion might beused. As a further alternative, a portion of the proximal end 12 oftubular body 11 is enlarged to a cross-section of a half inch or largerto facilitate grip. The enlarged section is provided with a plurality ofaxially slidable switches, one corresponding to each deflection wire 28.Manipulation of the switches by the thumb or forefinger will obtain thedesired deflection of steering region 16. As will be appreciated by oneof skill in the art, any control device will preferably be provided witha stop to prevent bending of the post 22 or steering region 16 past itselastic limit.

A variety of factors impact the amount of the lateral force componentexerted on steering post 22 by axial, proximal displacement of any ofdeflection wires 28. For example, as orifice 40 is moved further in aradially outward direction, the lateral force component will increase.Lateral displacement of orifice 40, however, is constrained by themaximum diameter that the steerable implement can have for an intendedapplication.

Alternatively, shortening the axial distance from the support 24 to thepoint of attachment 42 of the deflection wire 28 to the steering post 22increases the angle between the axis of post 22 and deflection wire 28,thereby increasing the lateral component of force. For this reason,support 24 is typically within one or two inches, and preferably lessthan one inch, from the distal tip 20 of an angioplasty catheter orguidewire embodiment of the invention.

A further alternative is illustrated in FIG. 5. In this embodiment, afulcrum 44 is provided at a point intermediate the radial support 24 andpoint of attachment 42 for maintaining the deflection wire 28 concave ina radial inward direction. The fulcrum 44 may conveniently comprise asubstantially radially symmetrical member such as a sphere or toroid,which can also function to limit proximal axial movement of steeringpost 22 through a central opening in support 24. In this embodiment, thepoint of attachment of deflection wires 28 may be to the fulcrum 44instead of directly to the steering post 22.

In accordance with a further aspect of the present invention, there isprovided a steerable medical implement for use in percutaneoustransluminal laser angioplasty applications. Referring to FIG. 4, thereis disclosed an elongate flexible implement 45 comprising at its distalend a floppy steering region 46. As described with previous embodiments,enhanced flexibility may be imparted to steering region 46 by providingspacing 47 between adjacent loops of wound wire 48.

A radial support means 49 is disposed at the proximal end of steeringregion 46, which may comprise a circular plate 50 or other structure fordisplacing deflection wires 52 radially outwardly from the axis ofimplement 45.

A waveguide such as a fiber optic bundle 54 extends the entire length ofthe implement 45, for directing laser light from a source (notillustrated) disposed at the proximal end of the implement 45, to apoint of application within a coronary artery at the distal tip 56 ofthe implement 45. For this purpose, the optical pathway 54 extendsthroughout the length of steering region 46 and traverses tip 56 by wayof an opening 58 therein.

Each of the deflection wires 52 is secured at its distal end to thefiber optic bundle 54 at a point intermediate radial support 49 anddistal tip 56. Preferably, as has been previously described, the pointof attachment of deflection wires 52 to the fiber optic bundle 54 isless than half the distance and preferably is within one-third of thedistance between the radial support 49 and distal tip 56, in order tooptimize the lateral component of force.

Thus, utilizing a control device as previously described, a laserangioplasty catheter incorporating the present invention permits thecontrolled direction of a beam of light transmitted through fiber bundle54 at any desired point within a full 360° circle on a plane normal tothe axis of the implement 45.

As is well known in the fiber optics art, numerous functions can beaccomplished through a waveguide such as fiber bundle 54. For example,substantially parallel but discrete bundles of fiber optics can besecured adjacent one another within the fiber bundle 54 to permit aplurality of discrete light transmitting channels. Alternatively, aplurality of concentric optical pathways can be provided as is wellknown in the art.

A plurality of discrete optical pathways may advantageously be used toperform a variety of functions. For example, a first optical pathwaymight be utilized to permit visualization of the stenotic site or othersurface to be treated. A separate optical pathway may be utilized totransmit light for illuminating the site. Yet a third optical pathwaymight be utilized to transmit the laser light. These and other aspectsof the fiber optics and laser light source are well known to thoseskilled in the fiber optics art.

A variety of additional functions may be performed through use of theadditional interior space within the housing of steerable implement 45.For example, in a preferred embodiment, an aspiration duct may beprovided near the distal end of the implement 45, for suctioning debrisor gases which may be generated as a result of the action of the laser.Alternatively, in place of a waveguide 54, a flexible tube may beincorporated into the steering device of the present invention, therebyproviding a working channel to receive additional implementstherethrough.

Referring to FIG. 7, there is disclosed a further embodiment of thesteering device in accordance with the present invention. The steerabledevice illustrated in FIG. 7 can be incorporated into a guidewire, ordirectly into a catheter, such as a balloon dilation catheter, or otherelongate implement for which steerability is desired. It is to beunderstood that while certain preferred dimensions and constructionmaterials will be recited in the discussion of the present embodiment,these illustrate a single angioplasty guidewire embodiment only and inno way limit the scope of the present invention.

The steering device 60 preferably is incorporated into a steerableguidewire, of the type made from an elongate flexible tubular springcoil 61 having a central lumen extending therethrough. The spring coil61 may be further provided with an outer sheath or coating, as are knownin the art, or the spring coil may, by itself, serve as the outer wallof the guidewire. As is well known in the art, the proximal end of thespring coil 61 is made up of a plurality of adjacent loops of wire.Lateral flexibility of the spring coil 61 at a distal steering regioncan be enhanced by providing a spacing between adjacent loops of thespring coil. These features are illustrated in FIGS. 1-6 of a previousembodiment of the present invention, and need no further discussionhere. Alternatively, the adjacent loops of wire in the steering regioncan be in contact with one another, i.e., no axial spacing, when thesteering region is in an orientation co-linear with the axis of theadjacent guidewire.

Extending axially within the steering region of the spring coil 61 is acentral post 62. Post 62 is preferably made from a flexible polymericextrusion, although any of a wide variety of materials can beincorporated into the post 62 of the present invention. Most preferably,the post 62 comprises a nylon rod having a substantially circularcross-sectional area and a diameter of about 0.004 inches.

The distal end 64 of post 62 preferably is disposed at or near thedistal end of the spring coil 61. For example, the distal end 64 in oneembodiment terminates proximally of the guidewire tip (not illustrated),similarly to the embodiment illustrated in FIG. 1. Alternatively, thedistal end 64 is in contact with the guidewire tip, which can be moldedor machined integrally with the post 62 or secured thereto such as byknown biocompatible adhesives. In either embodiment, the distal end ofthe spring coil 61 is provided with any of the known atraumatic tipsconventional in the angioplasty arts, such as those formed by molding ordipping or brazing processes.

Most preferably, the post 62 extends in a distal direction beyond thedistal ends of wire guides 72 and for a predetermined length. Provisionof such a length between the distal ends of the wire guides andeffective point of attachment of the pullwires causes the steeringregion in operation to form an "elbow" bend, which is believedclinically desirable. In addition, the portion of post 62 disposedbetween the end of wire guide 72 and the guidewire tip can function as asafety wire for securing the guidewire tip against in vivo detachment.

By "elbow" bend, it is meant that the bend in the guidewire occurs at arelatively discrete position displaced proximally from the distal end ofthe guidewire. This enables a short length of floppy guidewire at thedistal end to facilitate negotiation of the artery with minimal traumato the vascular intima.

The length of the floppy tip beyond the more rigid steering region ofthe guidewire can be varied, depending upon a number of considerationswhich will be apparent to one of skill in the art, including thediameter of the vessels expected to be traversed. In one specificconstruction of the embodiment of FIGS. 7 and 11, for example, therelative dimensions are as follows. Length of each of guide 68 andanchor 72: about 0.010 inches. Axial distance between guide 68 andanchor 72: about 0.006 inches. Distance between end of anchor 72 anddistal tip of guidewire: about 0.140 inches. Diameter of control post62: about 0.004 inches. Diameter of spring wire of guidewire body: about0.002 inches. Outside diameter of assembled guidewire: about 0.014inches.

The post 62 extends in a proximal direction through the spring coil 61as far as may be desired for a given application, as will be understoodby one of skill in the art. For example, the central post 62 may extendproximally only as far as the proximal wire guide 68, or further in aproximal direction to impart greater rigidity to the spring coil 61 thanwould otherwise be present.

The post 62 must at some point along its length be secured against axialmovement in the proximal direction relative to the spring coil 61. Froma manufacturing standpoint, it has been found convenient to secure theproximal wire guides 68 both to the post 62 and to the interior surfaceof spring coil 61 for this purpose as will be discussed. However, thepost 62 can also be secured to the coil 61 at other locations, such asat the proximal end of an axially elongated post 62.

A plurality of proximal wire guides 68 are provided for guiding each ofa plurality of deflection wires 70. Preferably, four proximal wireguides 68 are provided, equally spaced about the periphery of thecentral post 62. As will be apparent to one of skill in the art, threewire guides 68 spaced equidistant around the periphery of central post62 will also allow complete 360° steerability of the guidewire. However,the use of four deflection wires 70 is preferred. Similarly, theguidewire can be constructed having only two or even a single proximalwire guide 68, with a commensurate reduction in the range of motion overwhich the guidewire may be steered.

A plurality of deflection wires 70 extend axially throughout the lengthof the spring coil 61, each through a unique proximal wire guide 68 tothe distal end 64 of post 62. Preferably, the distal end 64 of post 62is also provided with a plurality of distal wire guides 72,corresponding to each deflection wire 70.

In accordance with the preferred embodiment of the present invention,four deflection wires 70 are utilized, each deflection wire 70 having aunique proximal wire guide 68 and distal wire guide 72. Each of thedeflection wires 70 may be secured to the distal end of the post in anyof a variety of manners, which will be apparent to one of skill in theart, such as by mechanical anchors, adhesives or thermal or chemicalwelding.

Mechanical anchoring or welding of the distal end of deflection wire 70may be difficult to accomplish while providing sufficient strength toallow repeated steering maneuvers of the steering device 60 withoutseparation of the distal end of deflection wire 70 from the distal end64 of post 62. Thus, although the preferred embodiment is effectivelyprovided with four deflection wires 70, they are actually two continuousdeflection wires which loop across the distal end 64 of the post 62. Afirst deflection wire 70 extends distally through distal wire guide 72,continuously around or over the distal end 64 of central post 62 andback proximally through the opposing wire guide 72 and continuing ontowards the proximal end of the instrument. In this manner, all fourends of the two continuous wires terminate at the proximal end of theguidewire where they connect to a control device permitting selectiveaxial reciprocating motion thereof.

In accordance with one preferred embodiment of the present invention,proximal wire guide 68 is in the form of an elongate tubular body forreceiving the corresponding deflection wire 70 therethrough. The tubularwire guide 68 preferably is comprised of a material which can be readilyadhered to the central post 62, and preferably also can be adhered tothe adjacent loops of spring coil 61. Polyamide tubing, such as thatmanufactured by Polymicro Technologies, Inc. in Phoenix, Ariz., havingan axial length of approximately 0.010 inches and an inside diameter ofslightly greater than 0.0015 inches, preferably about 0.002 inches, hasbeen found particularly suitable for this purpose, and can be readilyadhered to a nylon post 62 using a suitable epoxy adhesive, such as thatmarketed under the name Ecobond by Emmerson Cuming of Canton, Mass. Thelength of the tube is less important than the diameter, and the diametermust be sufficient that a deflection wire extending therethrough iscapable of reciprocal motion with sufficiently low friction thatsteering may be accomplished. The wall thickness of the tube willdirectly affect the minimum diameter of the assembled steerableguidewire, and is thus preferably minimized. For the polyamide tubedisclosed above, the wall thickness is preferably as low as about 0.0003inches. As illustrated in FIG. 8, the proximal wire guide 68 isconveniently affixed to the spring coil 61 by applying an epoxy 69thereto.

Deflection wire 70 extends distally beyond the end of the proximal wireguide 68, and preferably through a distal wire guide 72. Deflection wire70 is a fine wire of a diameter sufficient to provide enough tensilestrength to allow steering of the guidewire without breaking, but smallenough to permit construction of guidewires suitable for angioplastyapplications. Preferably, a stainless steel wire is used, and diametersas low as about 0.0015 inches have been found functionally sufficient.However, a variety of other metals or polymers may be used, and theminimum appropriate diameter for any given material can be readilydetermined by one of skill in the art.

Distal wire guide 72 is in the preferred embodiment a similarconstruction to proximal wire guide 68. Thus, distal wire guides 72 areformed by a plurality of elongate tubular guides adhered to the centralpost 62 for receiving the corresponding deflection wire 70 therethrough.Alternatively, the distal wire guide 72 can simply be a groove over thedistal end 64 of post 62, or a bore hole extending transversely throughthe center of central post 62.

Assembly of the steering device of the present invention may beaccomplished in a variety of ways which will be understood by one ofskill in the art, with many of the assembly steps being performed undermicroscopic vision. The proximal wire guide 68 and distal wire guide 72,when used, are preferably secured to the central post 62 by applying anadhesive thereto such as by dabbing with a 0.0015 inch diameter wire asan applicator. A first deflection wire 70 is threaded in a distaldirection through corresponding proximal wire guide 68, through distalwire guide 72, then back in a proximal direction through thecorresponding wire guides on the opposite side of post 62 and drawnthrough to the proximal end of the instrument. This assembly procedureis repeated for a second deflection wire. With the deflection wires 70in place, the entire distal end 64 of post 62 is dipped in or dabbedwith an epoxy or other biologically compatible material to form a cap 65to secure each of the deflection wires 70 against axial movementrelative to the control post 62. See FIG. 11.

The entire assembly of post 62 wire guides and deflection wires isthereafter inserted distal end first into the proximal end of a standardspring coil 61 and advanced until the proximal wire guide 68 isapproximately axially adjacent the beginning of the distal flexiblesteering region on the spring coil 61. An epoxy or other biocompatibleadhesive 69 is thereafter applied between the adjacent loops of springcoil 61 to secure the proximal wire guides 68 to the spring coil 61,thereby preventing axial movement of the post 62 relative to the springcoil 61. It has been found that polyamide tubing can be epoxied to theadjacent spring coil 61 using a 0.002 inch wire or other applicator tipunder microscopic vision. However, care must be taken that the epoxydoes not flow into contact with the deflection wire 70, in which casethe deflection wire 70 would be unable to slide axially within theproximal wire guide 68.

Referring to FIGS. 8-10, there is disclosed a further embodiment of thesteering device in accordance with the present invention. The steeringdevice 76 comprises a main body 77 having a proximal wire guide 80, awire anchor 84 and a pivot region 86. Preferably, the wire guide 80,pivot 86 and anchor 84 are integrally formed from a single extrusion ormolded part.

In accordance with a preferred embodiment of the invention, the mainbody 77 has a maximum diameter of as small as about 0.009 inches orsmaller, and is substantially circular in outer cross-sectionalconfiguration, except for a plurality of axially extending channels 85for receiving guidewires 88 therethrough. Each of the channels 85preferably has a depth of approximately 0.002 inches, so that0.0015-inch diameter stainless steel wire can slidably extendtherethrough. Channels 85 can conveniently be formed in the extrusionprocess as axial recesses of the type illustrated in FIGS. 8-10, or byproviding parallel sets of radially outwardly extending flanges whichextend axially to create a channel 85 therebetween.

Pivot 86 may be formed in any of a variety of ways, which will beapparent to one of skill in the art, and which will depend upon theconstruction material utilized. For example, in the case of athermoplastic polymeric extrusion, the pivot region 86 preferablycomprises a radially inwardly extending annular depression, which may beformed by application of heat and pressure or by stretching followingthe extrusion process. Alternatively, the pivot region 86 can beprovided by producing an annular recess through other operations such asby physically milling or cutting portions of the extrusion away, or,wire guide 80 and anchor 84 can be secured to a length of metal orpolymeric wire, spaced axially apart to provide a flexible length ofwire therebetween.

Preferably, the steering device 76 is provided with a deflection wire 88at each of the four 90° positions around the periphery thereof. (SeeFIG. 9.) As has been previously discussed, this can be accomplished byproviding four separate guidewires which are anchored at the distal endof the steering device 76. However, four deflection wires 88 areeffectively provided by assembling the steering device 76 with twocontinuous deflection wires 88, which loop over the distal end of wireanchor 84 and extend back in a proximal direction as has been discussed.

In assembling the embodiment of the steering device 76 illustrated inFIGS. 8-10, the deflection wires 88 are preferably crossed over thedistal end of an extruded main body 77, axially aligned with the freeends extending in the proximal direction. The distal end of the wireanchor 84 is thereafter dipped in or dabbed with an appropriateadhesive, such as an epoxy, to form a cap 90 for securing the deflectionwires 88 to the wire anchor 84.

A tubular sleeve 82, such as a length of heat-shrink tubing, isthereafter passed over the distal end of wire anchor 84 and advancedproximally into alignment with the proximal wire guide 80 in a mannerwhich captures each wire 88 within the respective channel 85. Uponapplication of heat, the annular sleeve 82 reduces in diameter to snuglyadhere to the proximal wire guide 80. It has been found that the use ofchannels 81, having a depth of approximately 0.002 inches, leaves asufficient tolerance after heat shrinking of sleeve 82 so that stainlesssteel wires having a diameter of approximately 0.0015 inches can freelyaxially move therethrough.

The steering assembly is thereafter inserted into a standard guidewirecoil 78, and advanced until the proximal wire guide 80 is approximatelyaligned with the distal end of the flexible steering region of the coil78. The radial outside surface of the annular sleeve 82 may thereafterbe secured to the adjacent coil loops of coil 78, such as by theapplication of an epoxy or other adhesive 79, as has previously beendescribed.

As will be apparent to one of skill in the art, axial movement of anygiven deflection wire 88 in a proximal direction will cause the wire 88to slide through the channel 81 in proximal wire guide 80, and, becausethe wire 88 is immovably secured to the wire anchor 84, pivot region 86will flex to permit lateral displacement of wire anchor 84 in thedirection of the wire 88 which has been proximally displaced. In thismanner, as has been described, the steering device 76 permits selectivelateral displacement of the distal tip in any direction, and restorationof the position of the distal end of the steering device back into axialalignment with the axis of the adjacent portion of the guidewire orcatheter.

In a modified version (not illustrated) of the device illustrated inFIGS. 8-10, the pivot region 86 is deleted so that the assembled devicehas an anchor region 84 and a wire guide 80 axially spaced apart andsecured to the coils of guidewire body 78. Thus, no post appears in thisembodiment. In this embodiment, the deflection wires extend distallyfrom the wire guide 80 toward the anchor 84 as before, but instead ofextending substantially parallel to the axis of the steering device 76as illustrated in FIGS. 8 and 10, each deflection wire crosses the axisof the steering device to the opposite side thereof. Thus, for example,one deflection wire 70 extends through wire guide 80 at the 90°position, then distally at an incline relative to the axis of thesteering device to the 180° position on the anchor 84. The wire 70thereafter in the preferred embodiment loops around the distal end ofanchor 84 and extends proximally through the channel 85 at the 90°position thereof. Wire 70 thereafter extends diagonally across the axisof the steering device, through the wire guide 80 at the 180° position,and proximally to the steering control.

As a further alternative, the distal ends of the deflection wires (whichmay be the midpoint of a long, doubled back wire as previouslydiscussed) are brazed directly to the wire coils of the guidewire body.A brazed joint is most conveniently accomplished on the outside surfaceof the guidewire body, and the deflection wires preferably extendradially outwardly between adjacent loops on the guidewire body for thispurpose. In the case of two deflection wires formed from a single lengthof wire looping around the steering region of the guidewire, thedeflection wire is conveniently looped around the outside of theguidewire body to provide a site for brazing. When a brazed joint isused, the distal wire anchor 84 can be deleted.

Referring now to FIGS. 12 and 13, there is shown in FIG. 12 a partialsectional perspective view of a two-wire steering device 100 with theouter tubular casing removed. FIG. 13 shows a partial elevationalperspective view of a another embodiment of a two-wire steering device120 according to the present invention. The tubular outer body 111 ofthe simplified steering devices 100, 120 can be similar to that of anyof the various embodiments previously described.

In the simplified steering devices 100, 120 shown, there is provided aflexible steering ribbon 110 disposed within the central lumen of thesteering region 116 of the tubular outer body. As will be discussed,"flexible" can mean either a ribbon which can be physically bent orflexed in use, or a more rigid structure provided with a narrowingthereon to form a hinge. In this embodiment, rather than complete 360°steerability, controlled steerability within a single plane is achieved.The improvement over the prior art is that the steering region of thedevice, once controllably bent, can be restraightened by applying apositive traction to one of the deflection wires.

The steering ribbon 110 may be molded, milled or extruded of any of avariety of known flexible materials, such as spring steel, nylon orother plastic materials. Preferably, the material will permit sufficientlateral flexibility while also exhibiting sufficient axial compressivestrength to optimize transfer of axial force into lateral deflection. Ina preferred embodiment, ribbon 110 is constructed of nylon.

The steering ribbon 110, as shown, is preferably of substantiallyrectangular cross-section. However, different cross-sections anddimensions may also prove suitable. Preferably, any cross section whichpromotes flexibility in a single plane may be provided.

For example, flexibility in a single plane can be facilitated by anappropriate pinching or narrowing of the ribbon 110 such as thatsometimes referred to as a "living hinge". See FIG. 13. This type ofhinge may be formed in a ribbon 110 of any cross-sectionalconfiguration, by molding, pinching, milling or stretching operations toform a narrowing having a greater propensity to bend than other portionsof the ribbon 110. Preferably, the hinge is formed by pinching in aribbon 110 having a rectangular cross section, however, anycross-sectional configuration may be used so long as flexibility in asingle plane is encouraged and the ribbon 110 has sufficient rigidityand strength to withstand the forces applied in multiple flexings andstraightenings needed in steering the body 111.

At least one deflection wire 170 is secured with respect to the ribbon110. In a preferred embodiment, there are two deflection wires 170, oneon each of two opposing sides of the ribbon 110 with the distal mostportions of the deflection wires (which may be the midpoint of acontinuous, doubled back wire as previously discussed) secured withrespect to the steering ribbon 110 such as by brazing directly to thesteering ribbon. A brazed joint may be accomplished as previouslydescribed.

Referring to FIG. 13, a hinge 175 is provided along the ribbon 110 whichprovides a predicted bending point along the ribbon 110 when thedeflection wires 170 are displaced. In the embodiment shown by FIG. 12,the hinge is effectively provided by an axial space between a wire guide172 and anchor 168 which can be similar to those described in connectionwith the embodiment illustrated in FIG. 7. In a preferred embodimentthere is one guide 172 and one anchor 168 on each side of the ribbon 110for each of two deflection wires 170. The two guides 172 and anchors 168are disposed opposite each other to provide the hinge 175 as the spacetherebetween. The guides 172 and anchors 168 function to secure thewires to the steering ribbon as described in connection with FIG. 7 forsecuring the wires 70 to the steering post. The length, diameter,positioning, construction and assembly of the guides 172 and anchors 168will be readily understood by one of skill in the art by reference tothe drawings and description above in connection with FIG. 7.

In the embodiment shown in FIG. 13, the hinge 175 is provided by anindentation 176 within the ribbon 110. This form of hinge is known as aliving hinge due to the tendency of the hinge to return to its originalposition. Other forms of living hinges may also be provided. Forexample, the hinge 175 can be produced by providing a cut out portion inthe ribbon, or can be provided by any known method of providing a hinge.Alternatively, the inherent flexibility of the ribbon may be usedwithout the provision of a hinge. See FIG. 12.

In another embodiment of the simplified steering device 100, thesteering ribbon 110 may be replaced with two or more substantiallyparallel ribbons.

In use, the steering device 100 or 120 can be steered in either of twodirectly opposite steering directions by displacing one of thedeflection wires 170. By axial displacement of either of the twodeflection wires, a range of motion of the tip of the device is achievedwithin a circular arc within a plane lying on the longitudinal axis ofthe steering device 100, 120.

After the device is introduced into the vasculature or other branchedsystem, and a branch or a turn is encountered, in order to enter thebranch or turn, the device can be rotated (torqued) to align one of thetwo steering directions with the branch or turn to be entered. Thedevice can be steered by axial displacement of one of the deflectionwires. Advantageously, after the device has been steered toward onedirection, the device can be easily straightened by displacing thedeflection wire opposing the side toward which the device was steered.The device can then be further advanced through the vasculature.

It must be pointed out that the devices of the present invention canreadily be modified by one of skill in the art to allow lateraldisplacement in only a single direction instead of two opposingdirections. For example, the groove in a living hinge type device can beprovided on only a single side of the steering ribbon, or other meansfor stopping or resisting flexing in one direction can be employed aswill be readily apparent to one of skill in the art.

An advantage of the simplified steering devices 100, 120 of the presentinvention is that they can be operated in a manner similar to thatemployed on convention steering devices for coronary angioplasty andother medical procedures. Thus, one skilled in the art of the prior artprocedures could learn to manipulate the steering device of the presentinvention with little or no additional training.

Although this invention has been described in terms of certain preferredembodiments, other embodiments that are apparent to those of ordinaryskill in the art are also within the scope of this invention.Accordingly, the scope of the invention is intended to be defined onlyby reference to the appended claims.

We claim:
 1. A steerable guidewire for percutaneous transluminalinsertion into the coronary vascular system and controlled negotiationof branches and turns therein to guide an angioplasty catheter to anarterial stenosis or other treatment site, said guidewire comprising:anelongate flexible housing having a proximal and a distal end and atleast one lumen extending therethrough; a flexible steering ribbonsecured within the lumen, and adapted to displace the distal end of thehousing in a lateral direction; at least one deflection wire guidedisposed on the steering ribbon; at least one deflection wire anchordisposed on the steering ribbon distally of the wire guide; and at leasttwo deflection wires axially movably disposed within the lumen of theflexible housing and extending from a distal point of attachment to thewire anchor throughout the length of the flexible shaft to the proximalend thereof;wherein axial movement of one of said deflection wires in aproximal direction displaces the axis of a portion of the housing in alateral direction and axial movement of the other of said deflectionwires in a proximal direction returns the axis of a portion of thehousing to its original, undisplaced position.
 2. A steering device forcontrolling a flexible steering region on the distal end of an elongateimplement, comprising:a steering ribbon positioned within the steeringregion of said elongate implement; at least two deflection wire guideshaving proximal and distal ends positioned on each of at least two sidesof said steering ribbon; at least two deflection wires secured relativeto the steering ribbon and extending proximally adjacent the deflectionwire guide;wherein axial proximal displacement of a first of said twodeflection wires causes the steering region to be displaced laterallysuch as to negotiate a branch or turn in an artery and axial proximaldisplacement of the second of said two deflection wires causes thelaterally displaced steering region to substantially straighten outagain.
 3. A steering device as in claim 2, wherein the elongateimplement comprises a flexible catheter.
 4. A steering device as inclaim 2 wherein the elongate implement comprises a flexible guidewire.5. A steering device as in claim 2, wherein said steering ribbon is ofrectangular cross section.
 6. A steerable guidewire for percutaneoustransluminal insertion into the coronary vascular system and controllednegotiation of branches and turns therein to guide an angioplastycatheter to an arterial stenosis or other treatment site, said guidewirecomprising:an elongate flexible shaft having a proximal and a distal endand at least one lumen extending therethrough; a flexible steeringribbon secured within the lumen, and adapted to displace the distal endof the housing in a lateral direction; a hinge on the steering ribbon toprovide a predicted flexing point along the ribbon; and at least twodeflection wires secured to the ribbon;wherein movement of the first ofthe two deflection wires in a proximal direction along the housingdeflects the distal end from a first position to a second position andmovement of the second of the two deflection wires in a proximaldirection deflects the distal end from the second position back to thefirst position.
 7. A steerable guidewire as in claim 6, wherein said atleast two deflection wires are spaced directly opposite each other withrespect to the steering ribbon so that selective proximal movement ofthe deflection wires will result in a range of motion of said tip withina plane which includes the axis of the flexible shaft.
 8. A steerableguidewire as in claim 6, wherein said hinge comprises a living hinge. 9.A steerable guidewire as in claim 6, wherein said hinge comprises anindentation in said steering ribbon.
 10. A steerable guidewire as inclaim 8, wherein said hinge comprises a cut out portion in the steeringribbon.
 11. A steerable implement as in claim 6, wherein said hingecomprises a space between two axially separate components disposed onsaid ribbon.
 12. A steerable implement as in claim 11, wherein saidcomponents comprise a steering guide and anchor.
 13. A steerableimplement, comprising:an elongate flexible housing having proximal anddistal ends and a central lumen extending therebetween, the distal endof the housing being flexible in a lateral direction; an axiallyextending steering ribbon secured in the housing, and adapted todisplace the distal end of the housing in a lateral direction, saidsteering ribbon having a hinge thereon for allowing motion in either oftwo directly opposite directions; at least two deflection wires havingproximal and distal ends extending along the housing, said wires beingsecured to the steering ribbon; and a control at the proximal end of thehousing for engaging the proximal ends of the deflection wires to enablesaid deflection wires to be displaced axially, in relation to saidimplement;wherein the axis of at least a portion of the steering ribbonis displaced laterally in one of the directions of movement of saidhinge in response to axial displacement of the first of said deflectionwires, thereby causing the distal end of said housing to bend out of theline of the housing longitudinal axis, and the axis of the displacedportion of the steering ribbon is returned to its original position byaxial displacement of the second of the deflection wires.
 14. Asteerable implement as in claim 13, comprising two deflection wires. 15.The implement of claim 13, further comprising a flexible tip attached tothe distal end of the housing.
 16. A steerable implement as in claim 13,wherein the cross-sectional area of the steering ribbon at the hinge isless than the cross-sectional area of the steering ribbon adjacent tothe hinge.
 17. A method of steering a guidewire through branches andturns in the coronary vascular system, said guidewire of the type havingat least two deflection wires for steering said guidewire and anelongate flexible shaft with a proximal and a distal end, said distalend being provided with a tip which is deflectable out of alignment withthe adjacent portion of guidewire to negotiate a turn and then back intosubstantial alignment with the adjacent portion of guidewire, saidmethod comprising:introducing said guidewire into the coronary vascularsystem; advancing said guidewire through the coronary vascular systemuntil a turn is encountered; rotating said guidewire until said turn isaligned with a direction in which said tip is deflectable; steering saidtip of said guidewire into said turn by axial displacement of a first ofsaid deflection wires to deflect the tip out of alignment with theadjacent portion of guidewire and in the direction of the turn;advancing said guidewire through said turn; and thereafter substantiallystraightening said guidewire by axial displacement of the second of saiddeflection wires.
 18. A steerable guidewire for percutaneoustransluminal insertion into the coronary vascular system and controllednegotiation of branches and turns therein to guide an angioplastycatheter to an arterial stenosis or other treatment site, said guidewirecomprising:an elongate flexible housing having aproximal and a distalend and at least one lumen extending therethrough; a flexible steeringribbon secured within the lumen, and adapted to displace the distal endof the housing in a lateral direction; at least two deflection wiresaxially movably disposed within the lumen of the flexible housing andextending from a distal point of attachement to the steering ribbonthroughout the length of the flexible shaft to the proximal end thereof;and wherein axial movement of one of said deflection wires in a proximaldirection displaces the axis of a portion of the housing in a lateraldirection and axial movement of the other of said deflection wires in aproximal direction returns the axis of a portion of the housing to itsoriginal, undisplaced position.
 19. A steerable guidewire as in claim18, further comprising a hinge on the steering ribbon.
 20. A steerableguidewire as in claim 19, wherein the hinge comprises a region ofreduced rigidity in the steering ribbon.
 21. A steerable guidewire as inclaim 19, wherein the cross-sectional area of the steering ribbon at thehinge is less than the cross-sectional area of the steering ribbonadjacent to the hinge.